1. Field of Invention
This invention relates to paper making processes, pulping mills and manufacture at fully integrated pulp and paper mills and to raw influent treatment processes for reducing Chemical Oxygen Demand, Total Organic Carbon, and Color in these raw influent streams in production of pulp and paper; and it does have other applicability to other industrial and municipal Publicly Owned Treatment Works (POTW) effluent treatment. Secondary biological treatment is eliminated.
2. Description of Prior Art
Large amounts of water are used in various stages of the pulping, bleach plant, and papermaking processes. At the DeRidder, La., mill of Boise Cascade where I was Corporate Environmental Engineer the average raw influent wastewater flow was 30 million gallons per day. The paper making processes such as at Boise's mill included bark removal, pulping digesters, chlorine, hypochlorite, and caustic extraction operations in bleach plant, three combination power boilers, chemical recovery boiler, lime kiln, groundwood, and thermomechanical pulping. Boise's DeRidder, La., mill discharged an average of 30 to 37.5 million gallons per day of wastewater to a small low flow stream Anacoco Bayou.
The raw influent wastewater stream 1, in FIG. 1, is contaminated with lignins, lignin degradation products, humic acids, and sulphates attached to ring structures, cellulose fibers, cooking chemicals and like. These contaminants make the effluent stream dark colored, and are often referred to as color bodies. Since pulp and paper mills produce large quantities of this densely colored raw influent, a discharge of this effluent into adjacent streams and bodies of water causes an objectionable discoloration of the water.
In 1985 the Best Available Control Technology (BACT) in Clean Water Act, Public Law 92-500, and National Pollutant Discharge Elimination System (NPDES) effluent guidelines had Color limits of 200 to 250 milligrams per liter concentration limits for Color. These proposed Color limits were eventually deleted. When this becomes fully vamped into the public domain and at EPA's leadership and industry's leadership, everyone wins. Industry will have immediately more expansion capacity capability at all their operating plants and will save tremendous amounts of electrical energy. Furthermore, streams accepting industries' wastewater will have extremely more assimilative capacity to accept wastes and protect human health and aquatic life.
FIG. 1 is a schematic representation of a typical integrated pulp and paper plant's wastewater treatment system, typical for Boise's DeRidder, La., mill. The raw influent stream 1, in FIG. 1, is the main influent sewer entering a clarifier. In all mills nationwide no chemicals are added, and only gravity settling is utilized. The average pH of raw influent is in range of 7.5 to 8.5; and this was true for Boise's DeRidder raw influent. Various processes have been proposed for decolorization at this stage; however all other state of art dictate that biological secondary treatment is additionally required. This invention is an improvement as it eliminates the secondary biological treatment. When this becomes into the public domain, other old art and patents already issued may be also commercialized. Additionally, all other prior art are that there is no biological degradation. In the United States there are approximately 950 pulp and paper mills where no chemicals are added at a clarifier. There is no change, no reduction in the Chemical Oxygen Demand, Total Organic Carbon, and Color across a clarifier and aerated secondary biological system, activated sludge, and all other biological aerated systems. All other old art were not aware that there was never, ever any biological degradation, destruction in secondary biological systems.
As in Fuller, U.S. Pat. No. 3,627,679 the inventor, states “the need for biological treatment of pulp and paper mill effluent has forced the art to include effluent disposal systems of greater or lesser efficacy as an almost integral part of a pulp and paper mill complex.”
As in Siefert, et al, U.S. Pat. No. 5,200,089 the inventor states the following: “Once the suspended solids have been precipitated in basin 3, the effluent stream moves through channel 5 into bio-degradation basins 7 and 9. The pH of the stream entering the biodegradation basins 7 and 9 must be between pH 7 and 8 in order to prevent damage to micro-organisms in the basins.”
As in Ackel, U.S. Pat. No. 4,724,045 Ackel states the following: “and then on to be biologically treated 16 to remove BOD. Such biological treatment and the methods of biological treatment are well known in the art.”
As in Lind, et al, U.S. Pat. No. 5,766,485 Lind, et al, states the following: “Suspended solids can be readily removed and organic materials that use up oxygen, that is, that have a high biochemical oxygen demand (BOD), can also be generally removed using existing technologies.”
Thus, the inventions of Fuller, U.S. Pat. No. 3,627,679; Siefert, et al, U.S. Pat. No. 5,200,089; Ackel, U.S. Pat. No. 4,724,045 and Lind, et al, U.S. Pat. No. 5,766,485 may be commercialized more rapidly with the discovery of my invention that secondary biological treatment may be and shall be eventually eliminated.
However, as discussed and described in this invention that there are actually no biological treatment, no biological degradation and no bugs eating and degrading organics. Additionally, that the Biochemical Oxygen Demand test for these pulp and paper mill wastewater has some severe loop-holes and is detrimental to the environment and water quality. As noted in Lind, et al, U.S. Pat. No. 5,766,485, the inventor points out that Fuller process has not been adopted widely because of three reasons. In Lind, et al, U.S. Pat. No. 5,766,485 alum process residues (APR) were used to remove colored contaminants. However Lind, et al, U.S. Pat. No. 5,766,485 as well as Fuller, U.S. Pat. No. 3,627,679; Siefert, et al, U.S. Pat. No. 5,200,089; Newton, U.S. Pat. No. 4,201,666 and Ackel, U.S. Pat. No. 4,724,045 all considered that secondary biological aeration treatment could not be eliminated. And, as well, this was stated and known art of treatment in pulp and paper mills wastewater. The basic premise was, when I joined Boise's DeRidder Mill, even though the wastewater discharged had a Color concentration of 3000 to 5000 milligrams per liter, there wasn't anything harmful in the wastewater, and it would cost millions of dollars to clean the wastewater. Basic premise is “it is too expensive, and secondary biological treatment is satisfactory.” Thus, I was told if we now spend $5,000,000 for biological treatment; it is not economically feasible to spend another $5,000,000 for Color Removal. However, with my discovery and the facts revealed that there are zero reduction of COD and TOC from secondary biological treatment, this basic premise fails. In reality, the 800 to 1000 milligrams per liter Chemical Oxygen Demand, the 300 to 600 milligrams per liter Total Organic Carbon, and the 2500 to 5000 milligrams per liter Color are being discharged to our nation's navigable waters. Therefore as well as all the other 900 integrated pulp and paper mills in the United States, there is no biological degradation taking place in the aerated stabilization basins, activated sludge, and all other aeration systems. This invention needs to become into “the public domain.” It is imperative for the U.S. Environmental Protection Agency and all fifty states' environmental control agencies to immediately become aware of a loop hole in the Biological Oxygen Demand (five day test). There may become an urgency of revising all pulp/paper mills' NPDES wastewater permits to reflect new Chemical Oxygen Demand limits.
Conventional early treatment processes such as precipitation of the suspended solids with lime, polyelectrolyte polymers or inorganic metallic salts are effective in removing some color from such effluent. Some polyelectrolyte polymers at high dosage rates are prohibitively expensive and technically unfeasible for treating large quantities of wastewater generated by commercial size pulp and paper plants. Inorganic metallic salts produce a great deal of solids; however when secondary biological aeration treatment is eliminated there is a tremendous cost savings in electricity for the electrical aerators and maintenance of these aeration equipment. This will encourage commercialization of prior art and this invention. And in this invention, burning the dewatered solids in existing combination bark/oil/gas/coal fired combination boilers rewards the industry with credits for electrical energy saved by utilizing the resultant energy (BTU content) of the dewatered solids, plus the several annual millions of dollars saved annually by turning-off all electrical aeration equipment. Furthermore, the reduction and high removal efficiencies for Chemical Oxygen Demand and Total Organic Carbon across a clarifier renders this technology to be very cost-effective.